“Flip chip” fabrication, also known as controlled collapse chip connection (C4), is a manufacturing method for interconnecting semiconductor devices, such as integrated circuit (IC) chips, to external circuitry with balls of solder, called “bump bonds,” deposited onto chip pads on the top side of a first chip near the end of a wafer process used to fabricate the first chip. To mount the first chip to external circuitry (e.g., a circuit board or a second chip or wafer), the first chip is flipped over so that what was initially its top side during its own fabrication faces down, and then is aligned so that its pads align with matching pads on the external circuitry. Flip chip fabrication stands in contrast to wire bonding, in which a chip is mounted upright and wires are used to interconnect the chip pads to external circuitry. Flip chip processes are used in making traditional CMOS devices, and now also in the construction of superconducting circuit devices that typically operate in refrigerated cold spaces.